Effect of baffle height and Reynolds number on fluid mixing

In this paper, both numerical simulation and experiment were performed to investigate the mixing process within mixing chambers of the planar micromixer with three baffles at varied baffle height. The presence of three baffles causes the flow to separate and creates the recirculation and back flow within mixing chambers. The fluid mixing was greatly influenced by the baffle height and Reynolds number (Re) related to the size of recirculation zone. Larger baffle height or Re produces larger recirculation zone and convective mixing. The micromixer with 350 μm high baffles in 400 μm wide channel results in over 95% mixing at Re = 80 from the simulation results. The experiment results confirm the above simulation results qualitatively. This planar micromixer has the merits of simple design and easy fabrication as compared to the three-dimensional passive micromixers.